Apple will launch an upgrade to its low-end desktop, the Mac Mini, at January's Macworld Expo in San Francisco, according to an Apple corporate employee who contacted Wired.com.

The source, who wished to remain anonymous (to keep his job), could not disclose details about the Mac Mini other than its upcoming announcement at Macworld Expo, which begins Jan. 5. That's where CEO Steve Jobs traditionally launches major products during his famous keynotes (assuming he does indeed show up).

Here's what Wired.com believes will be in the next Mac Mini, based on trends seen in Apple's latest products:

Similar to the MacBooks, the Mac Mini will sport a silver enclosure composed of a block of aluminum.

Some internal parts will be PVC-free, and combined with its size and low power requirements, Apple will tout this as the "greenest Mac ever."

For video output, the Mac Mini will use the DRM-crippled DisplayPort for connectivity, which Apple is offering to manufacturers for a no-fee license.

It'll have a CD-DVD slot loader (i.e. Super Drive). There will be no Blu-ray player, because Steve Jobs believes the format is a "bag of hurt."

It'll ship with 2 GB of RAM, expandable to 4 GB - up from the current 1 GB, expandable to 2 GB. (The aluminum case should make expanding RAM easier than in the original Mini.)

It'll ship with at least a 160-GB hard drive.

The Mac Mini will come in two options with different processor speeds: a 2.0-GHz Core 2 Duo and a 2.3-GHz Core 2 Duo (up from 1.83 GHz and 2.0 GHz).

Like the higher-end MacBook and MacBook Pro, the 2.3-GHz Mac Mini will ship with an Nvidia video card, making this higher-end model a decent gaming device.

The 2.0G-Hz Mac Mini will ship with an Intel video card, perhaps the GMA X3100 graphics card found in the low-end, white MacBook.

The slower model will cost $500, and the faster model will cost $700 ($100 less than the current Mac Minis), in light of the recession.